16х4+4х2-2=0
cos(1,5п+6x) - sin (-2x) / 1+cos (-4x)=(sin6x+sin2x)/(1+cos4x)=2sin4xcos2x/2cos^2 (2x)=sin4x/cos2x=2sin2xcos2x/cos2x=<u>2sin2x</u>